Merging data from two DC broken?

[Miika Turkia]

Hello,

here are a couple of notes I did during doing a bit of testing with
the current development version of Subsurface:

- Data from two dive computers are not merged (used on same dives), I
have no idea what has changed since this used to work. I tested this
with closing the divelog and starting a new one.
- It used to be - if I downloaded Stinger first (with no air
integration) and Vyper Air then, the air data from the second DC was
not used/shown. I just cannot verify this anymore as dives from my two
DCs are not automatically merged currently. (This was the case about a
month ago)

Other issues:
- If I have manually merged dives and download from computer again,
the merged dives pop up as new individual dives (3 dives merged and
re-download results in 4 dives in total)
  - Tracking merged dives in this scenario would be appreciated,
especially since the new ghost dives typically pop up somewhere deep
down in the divelist and only present themselves when renumbering
dives

- A possibility to merge dive location information from other log file
would be great (copying dive locations from my dives to my buddy's
logs, based on the fuzzy time merge)

miika